1. Field of the Invention
The present invention relates to a flat display device, and more particularly, to an active matrix (AM) flat display device having a thin film transistor (TFT).
2. Description of the Related Art
Flat display devices such as liquid crystal displays (LCDs), organic light emitting displays (OLEDs) or inorganic light emitting displays are divided into passive matrix (PM) flat display devices and active matrix (AM) flat display devices according to driving methods.
In PM flat display devices, anodes and cathodes are arranged in a plurality of columns and a plurality of rows, scanning signals are supplied to the cathodes from a row driving circuit, and in this case, only one row is selected from the plurality of rows. In addition, a data signal is input to each pixel by using a column driving circuit.
Meanwhile, AM flat display devices have been widely used as display devices which control a signal input to each pixel using a thin film transistor (TFT), and are appropriate for processing an enormous amount of signals and realizing moving images.
TFTs of AM flat display devices comprise a semiconductor active layer having source and drain regions doped with high-concentration impurities on a substrate and on a channel region formed between the source and drain regions, a gate electrode facing the active region of the semiconductor active layer, a gate insulating layer interposed between the semiconductor active layer and the gate electrode, and source and drain electrodes respectively contacting the source and drain regions of the semiconductor active layer.